1the Sweeper Monk: a nameless monk who sweeps the Shaolin sutra library in Jin Yong's novel Demi-Gods and Semi-Devils (天龙八部); by extension, an unassuming master whose true power is hidden
A nameless old monk who sweeps the library of the Shaolin Temple in 金庸's novel 《天龙八部》 and turns out to outclass every famous fighter. People now call any quiet, unnoticed expert a 扫地僧.
Tā píngshí bú ài shuōhuà, méi xiǎngdào shì gè sǎodìsēng.
He's usually quiet - turns out he was a hidden master all along.
Tips
memory
His name is just his chore: 扫地 'sweep the floor' + 僧 'monk'. In the novel he has swept the Shaolin sutra library for over forty years, quietly shelving Buddhist sutras beside the martial-arts manuals in the hope that thieves would read those too.